Root Cause Analysis: Looking at the given vulnerable code line and its context, the CWE-787 (out-of-bounds write) vulnerability exists in the code because the `kmalloc` function is used to allocate memory for `rule_buf` without checking if `info.rule_cnt` is zero. If `info.rule_cnt` is zero, then allocating memory with `info.rule_cnt * sizeof(u32)` will result in an out-of-bounds write vulnerability, which is CWE-787.